(19)
(11) EP 0 817 253 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
23.12.1998 Bulletin 1998/52

(43) Date of publication A2:
07.01.1998 Bulletin 1998/02

(21) Application number: 97303096.8

(22) Date of filing: 06.05.1997
(51) International Patent Classification (IPC)6: H01L 21/48, H01L 23/367
(84) Designated Contracting States:
DE FR GB

(30) Priority: 28.06.1996 US 672875

(71) Applicant: International Business Machines Corporation
Armonk, N.Y. 10504 (US)

(72) Inventors:
  • Bernier, William Emmett
    Endwell, New York 13760 (US)
  • Gaynes, Michael Anthony
    Vestal, New York 13850 (US)
  • Memis, Irving
    Vestal, New York 13850 (US)
  • Shaukatullah, Hussain
    Endwell, New York 13760 (US)

(74) Representative: Burrington, Alan Graham Headford 
Alan Burrington & Associates 4 Burney Close Great Bookham
Leatherhead, Surrey KT22 9HW
Leatherhead, Surrey KT22 9HW (GB)

   


(54) Attaching heat sinks directly to flip chips and ceramic chip carriers


(57) An aluminium or copper heat sink is attached to a ceramic cap or exposed semiconductor chip using an adhesive of silicon or flexible-epoxy adhesive. The aluminium may be coated by anodizing or Chromate conversion or the copper may be coated with nickel or gold Chromium. Such structures are especially useful for flip chip attachment to flexible or rigid organic circuit boards or modules such as CQFP, CBGA, CCGA, CPGA, TBGA, PBGA, DCAM, MCM-L, and other chip carrier packages in which the back side of chips are connected directly to heat sinks. These adhesive materials withstand wet or dry thermal cycle tests of -65 to 150° C for 1,000 cycles and 85°C and 85% relative humidity for 1000 hours while maintaining a tensile strength of at least 35 x 104 kg/m2 500 psi. The adhesive contains materials having high thermal conductivity and a low coefficient of thermal expansion (CTE) in order to provide increased thermal performance and a CTE between that of the silicon metal die and the metal of the heat sink.






Search report